The subject matter of the invention relates to strand of plastic and a line guide arrangement for running at least one line as well as a method of making a strand.
Line guide arrangements are used for running lines from a stationary connection to a movable consumer. Known are line guide arrangements, which comprise flexibly joined segments. Each segment includes side wall portions. The segments are formed by transverse separations of a strand. The transverse separations extend crosswise to the longitudinal direction of the strand. They are formed at selected distances from one another. In the side wall portions, the separations extend to the vicinity of a support wall portion. The strands enable a looping of the line guide arrangement. Such a configuration of a strand is disclosed in EP 0 544 027 A1.
Furthermore, EP 0 490 022 A1 discloses strands for a line guide arrangement. These strands are in part formed as special-section strands. The special-section strand comprises a support wall portion projecting substantially crosswise to a side wall portion, with transverse separations continuing through the side wall portion at least to the vicinity of the support wall portion. Thus-forned strands of plastic for a line guide arrangement are extruded from the plastic. The transverse separations are mechanically formed.
The strands of a line guide arrangement are subjected to a bending stress, when they form loops. This stress is dependent on the radius of curvature, which is realized, when the line guide arrangement is looped. Preferred are small radii of curvature, so as to limit the line guide arrangement to a small overall space.
These bending stresses repeatedly act upon the support wall portion, and may lead in the case of relatively rigid special-section strands to cracks in the material of the support wall portion. These cracks considerably influence the service life of the line guide arrangement.
Based on the foregoing, it is an object of the present invention to further develop the known strand as well as a line guide arrangement such that an increased service life is attained. A further object of the present invention is to describe a method of making a strand with an increased alternating bending strength.
According to the invention, these objects are accomplished by a strand of a line guide arrangement having the characteristic features of claim 1 and a method of making the strand comprising the steps of claim 11, 13, or 14. Advantageous further developments and improvements of the invention are subject matter of the dependent claims.
The strand of plastic for a line guide arrangement according to the invention possesses flexibly interconnected segments, which have side wall portions along the direction of the strand. These side wall portions are defined by transverse separations formed crosswise to the longitudinal direction of the strand, which extend at selected distances from one another to the vicinity of a support wall portion. The strand possesses at least in part at least one reinforcement fiber. The reinforcement fiber extends substantially parallel to the direction of the strand, and it is arranged substantially in the support wall portion. The use of at least one reinforcement fiber of this kind reduces an expansion of cracks in the support wall portion in case of frequent bending stresses, and thus raises the load cycle of the strand, thereby increasing its service life. It is preferred to arrange the reinforcement fiber substantially along the neutral axis of the strand. The neutral axis extends inside the support wall portion. In this way, the reinforcement fiber is subjected to little mechanical stress.
For further increasing the alternating bending strength of the strand, and thus likewise of the line guide arrangement, it is proposed to extend the reinforcement fiber at least over the entire length of the strand. In this manner, it is ensured that all segments of the strand perform similarly over a certain load cycle of the bending stresses.
According to a yet further advantageous embodiment of the strand for a line guide arrangement, it is proposed to extend the reinforcement fiber beyond the strand. The portions of the reinforcement fiber, which project on the face end beyond the length of the strand, serve as a point of attachment or connection. In this manner, the portions of the reinforcement fiber projecting from the strand may be connected to a further strand. Furthermore, these projecting portions of the reinforcement fiber may be connected to a wall mounting part. It will be especially advantageous to clamp the projecting portions of the reinforcement fiber with a connector, which reduces or prevents a movement of the reinforcement fiber relative to the strand. This accomplishes an absorption or transmission of tensile forces that occur from the strand to the reinforcement fiber.
According to a yet further advantageous embodiment, the reinforcement fiber extends on the support wall portion. Accordingly, the reinforcement fiber is arranged such that it enables a relative movement between the reinforcement fiber and the support wall portion. This presents the possibility of being able to mount the reinforcement fiber in a simple and detachable manner to the support wall portion.
Preferred is the embodiment of a strand, wherein the reinforcement fiber is attached at least in part to the support wall portion. This prevents a relative movement between the strand and the reinforcement fiber. A thus-realized attachment prevents signs of wear of the connection fiber and/or the strand, as result from the relative movement to each other and from the resultant friction on the surfaces.
Preferably, the reinforcement fiber is arranged such that it is surrounded at least in part by the material of the support wall portion. The construction of a device for applying the reinforcement fiber may thus be integrated into the production process of the strand, and further joining processes may be omitted.
According to a yet further advantageous embodiment of the strand, the reinforcement fiber exhibits a higher alternating bending strength and/or tensile strength than the support wall portion. A higher alternating bending strength and/or tensile strength of the reinforcement fiber in the support wall portion reduces the speed of the crack expansion, and clearly increases the attainable load cycle under bending stress. An increased alternating bending strength and/or tensile strength of the reinforcement fiber over the support wall portion may be accomplished with a material of the reinforcement fiber, which differs from the material of the support wall portion and/or a suitable constructional design of the reinforcement fiber.
It is preferred to make the reinforcement fiber as a steel wire. Based on its alternating bending strength and tensile strength characteristics, the steel wire increases the attainable load cycle under alternating bending stress. In comparison with other cross sectional profiles, a preferred, circular cross section of the steel wire reduces a development of cracks in the case of bending stress in the vicinity of the reinforcement fiber. The mechanical properties of the steel wire assist an easy loop formation of the line guide arrangement, in that the steel wire adapts itself to the required radius of curvature. According to further embodiments, the reinforcement fiber is formed at least in part from fiberglass, carbon fiber, KEVLAR(copyright) fiber, or textile fiber. KEVLAR(copyright) is a registered trademark of E. I. duPont de Nemours Company Corporation.
A yet further advantageous design of a strand for a line guide arrangement distinguishes itself in that the strand comprises a plurality of reinforcement fibers in the support wall portion, which extend preferably symmetrically to the side wall portion. This will be especially important, when the strand is designed and constructed as a special-section strand. The arrangement of a plurality of reinforcement fibers in the support wall portion substantially in symmetry to the side wall portion, enables a more even load distribution in the support wall portion.
According to a yet further concept of the invention, a line guide arrangement is proposed, wherein at least two, substantially parallel strands are interconnected with cross members, which are attached to opposite segments at selected distances from each other. In this instance, the segments and cross members define a guide channel for running at least one line. The parallel arrangement of the strands ensures that a line guide arrangement is present with a constant width. The cross members, which are attached to opposite segments, increase the torsional rigidity of the line guide arrangement. Thus, the increased alternating bending capability of the strands enables an increased service life of the line guide arrangement. The line guide arrangement may be designed and constructed according to the line guide arrangements disclosed in DE 19 839 966.9 and/or DE 19 840 012.8 and/or DE 19 837 231.0. The disclosure of these applications also forms the subject matter of the present application.
The method of the invention for making a strand of plastic for a line guide arrangement that comprises flexibly joined segments, which include side wall portions along the direction of the strand, and whose boundaries are transverse separations that are formed crosswise to the longitudinal direction of the strand, with the separations extending at selected distances from one another to the vicinity of a support wall portion, wherein the strand is extruded and the segments are formed, is characterized in that before or after forming the segments, at least one reinforcement fiber is provided substantially on the support wall portion and substantially parallel to the direction of the strand. Irrespective of the time, when the segments are formed, the at least one reinforcement fiber is provided on the support wall portion. To this end, additional joining methods and/or necessary devices may be used.
According to an advantageous variant of the method of making a strand of a line guide arrangement, it is proposed to form in the support wall portion preferably a longitudinal groove, and to insert into same the reinforcement fiber. The longitudinal groove makes it possible to run the reinforcement fiber on the support wall portion. In accordance with the shape of the longitudinal groove, it is possible to restrict the freedom of movement of the connection fiber. In addition, there exists the possibility of joining the reinforcement fiber to the support wall portion in the vicinity of the groove by means of further joining methods such that no relative movement is possible between the reinforcement fiber and the support wall portion.
A further advantageous concept proposes a method of making a plastic strand of a line guide arrangement, with the strand comprising flexibly joined segments, which include side wall portions along the direction of the strand, and whose boundaries are transverse separations formed crosswise to the longitudinal direction of the strand, the separations extending at selected distances from one another to the vicinity of a support wall portion, wherein the strand is extruded and the segments are formed, and wherein the at least one reinforcement fiber is inserted into the extrusion die during the process before the extrusion step. In so doing, the reinforcement fiber is positioned in the extrusion die such that it is arranged in or on the support wall portion after the curing process of the plastic. Thus, the attachment of the reinforcement fiber to the strand is integrated into the formation of the strand.